A biomechanical evaluation of hinged total knee replacement prostheses

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Biomedical Device Design

Background:

• Total knee replacements are increasing globally, with hinged prostheses used in complex cases.
• Hinged knee designs vary in hinge anteroposterior location, affecting biomechanics.
• A posterior hinge aims to reduce quadriceps force by increasing the patellar tendon moment arm.

Purpose of the Study:

• To evaluate quadriceps force and patellar tendon moment arm in five common hinged total knee replacements.
• To analyze the correlation between hinge location, patellar tendon moment arm, and quadriceps force.
• To investigate the influence of prosthetic patellofemoral geometry on joint function.

Main Methods:

• Laboratory-based rig testing of five distinct hinged total knee replacement designs.
• Measurement of quadriceps force and patellar tendon moment arm for each prosthesis.
• Correlation analysis to determine relationships between biomechanical parameters.

Main Results:

• Significant variations in quadriceps force and patellar tendon moment arm were observed among the five prostheses.
• Patellar tendon moment arm was found to influence quadriceps force.
• The patella's lever function and non-physiological prosthetic geometry also play a role in joint mechanics.

Conclusions:

• Hinged total knee replacement design, specifically hinge location, affects biomechanical outcomes.
• Quadriceps force is influenced by patellar tendon moment arm but also by patellar lever function and prosthetic geometry.
• Understanding kinematic function is vital for optimizing hinged total knee replacements in revision surgery.